Bug 1072305 - screen reader now handles gridcell, column and row headers more efficiently. r=eeejay

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 accessible/jsat/TraversalRules.jsm                 |  8 ++++
 accessible/tests/mochitest/jsat/test_output.html   | 46 ++++++++++++++++++++++
 .../tests/mochitest/jsat/test_traversal.html       |  8 ++--
 3 files changed, 58 insertions(+), 4 deletions(-)